This invention relates to metallizing compositions and, more particularly, to silver compositions, useful in the electronic arts.
Compositions of finely divided silver and glass powder, dispersed in a liquid vehicle, have been used in the electronic arts for many purposes, including printing thick-film patterns on glass surfaces for subsequent firing to produce automobile windshield demisters. When an electric current is applied to the patterns, the electric current develops heat and thus heats the glass surface. The automotive industry has produced back window demisters or heaters by applying silver stripes on the back window. The silver stripes are connected in parallel relationship and when an electric current is applied, the silver stripes act to remove mist and fog from the back window of the automobile. Typical of art on such silver compositions is my U.S. Pat. No. 3,350,341, issued Oct. 31, 1967, disclosing compositions of silver, vitreous binder and vehicle. Improved silver compositions comprising certain additive salts which have reduced tendency to produce objectionable back-side discoloration when fired on glass (such as auto windshields) include those of my U.S. Pat. No. 3,649,567, issued Dec. 29, 1971.
It has been found by the automotive industry that prior art silver compositions are observed to be deficient when sulfurized neoprene sealant is used to mount windshields in automobiles using the so-called "hot-wire" process. In this process the demister is printed and then fired onto a windshield, after which the windshield is mounted on the automobile with a "rope" of partially cured sulfurized neoprene. The rope of neoprene is melted into the windshield channel by passing current through a wire embedded in the rope. The silver in conventional demister patterns is, during this process, exposed to and attacked by sulfur. A silver composition less susceptible to such attack is desirable.
Neoprene (chlorobutadiene polymer often sulfur modified) is discussed generally in the "Encyclopedia of Polymer Science and Technology," John Wiley, N.Y., 1965, vol. 3, pp. 705-730. Sulfur-modified neoprene is, for example, disclosed in Collins U.S. Pat. No. 2,264,173, issued Nov. 25, 1941.